Mining



Reissued Nov. 19, 11 929 UNITED STATES;

P ENT mm HENRY RPOWER, or NIAGARA rAIfjLs, 'N-EwNonx,Assrs onfinvnsNnAssIGN- MENTS, 'ro mrNNnsorA MINING a MANUFACTURING "COMPANY, on ST.PAUL,

MINNESOTA, A1 CORPORATION or iui'NNnsorA WATERPRQOF; ABRASIVE NoDrawing. Qrig'inal No. 1,615,231; datedwJanua'ry25;:-1827,'-Serial+No..646,959,.fi1ed31l'une 21, 1923.

Application for reissuefiled November 9,1927, Serial No. 232,189.

My invention relates to waterproof sives, and particularly to thewaterproofing of:

abrasive. paper and cloth.

Abrasive paper or cloth is ordinarilymade by applying a coating of hotadhesive',-such as hide glue, bone glue, or vegetable glue, to

the surface of the backing, then runningzon a stream of abrasive grain,and allowing the product to,.cool. The ordinary adhesives-sin use forthis purpose ,are not waterproof anddo not permit of the elficient useof the abrasive paper with water which is required-in the process'ofrubbing certain kinds of varnish a flexible backing and abrasive grainsat tached thereto by a binder, the outer surfacethis operation I sprayor flow the waterproofing compound on both the face and theback of thebrasive paper or cloth. The water= proofing substance is preferablypyroxylin dissolvedjin a proper solvent, such as an ace-- tate likebutyl actate, with or without-otheracetates, an alcohol like ethylalcohol, with tone, methyl ketone, or acetone oils, benzol, and camphor.I find it possible to use in the solution of nitro-cellulose a resin,(so-called gum, or gum-resin), such as copal or damar. The solutionmentioned may vary within wide limits, and should be adjusted as to itsboiling point to prevent too rapid evaporation of the film and toprevent absorption of water which may weaken the film before it is set.

In order to get a form of nitro-cellulose which can be used in solutionand possess properties essential for operation on a production basis,such as even flowing or spreadin on the backing. used, there must beacering solvents to o tain the proper rate of :ment ofthe solution tothat ich is water solu le-, a nd v evaporation. .To get 'theresirnlikedamar,

intosolutiomand the intro-cellulose into solu- I tion, thelowen boilingsolvents, such as ethyl alcohol, acetone, andsan acetate are used. To

prevent too rapid evaporation: and. thus provideifor the proper flow ofthe material, additional-solvents of relatively .higheri boiling-poi-nts, such asbutylwand amyl acetates, the higher boiling (alCQh01S,=and certain ketones .are used. Low evaporation rate, produced byhigherboiling solvents; prevents cooling ofthe surrounding air-and theconsequent condensation of water on the lacquer surface. finish. Thewater loosens the grain fromthe paper and materially shortens its life.

I provide an abrasive product comprising.-

This in turnprevents precipitation ofthe nitroscellulose. ,Thus' theyimportant. adjust- J I proper boiling point is securejd. -Benzol11s used&St a C lll118IllJIaHd also as a solvent for the resinsuseicl because ofits comparatively low cost.- It functions! to reduce the viscosity ofthe nitrocellulose solution zcontaining resins'so.thatiitiseasier tomenipulate v in the abrasive; coating .process.

dum', emery, garnet, sand,or the like,=in theusual manner, and allowthem to set. After.-v

amphor .constitutes a, plasticizer or softener. softener. is to make theresulting film tough, elastic, flexible, adhesive and permanent.

The function of the resin is to, give adhesion,bodyand hardiness to thecoatingand. to

render the coating more imperviousto mcisturer" Thisincrease in thehardness of the film isavery desirable feature in: producing a good orwithout other alcohols, ketones, like aceabrasive paper because theabrasive grains on the paper undergo very severe service in the art ofrubbing or grinding the materials on which they are being worked, andibyin-.

creasing thehardness of the film the. grains are more firmly heldinplace and stick. on to the backing longer and more securely so thatthe. life of the abrasive article isin creased. The resin also increasesthebody of the coating material without increasing the viscositythereof, and this is highly'desirable. Being cheaper thannitro-cellulose, many resins tend to reduce the cost. In

creasing the hardness by the use of a resin, there is a tendencytobrittleness, and to oil'- set this and secure plasticity is one ofthefunctions of the plasticizer, s'uchas camphor.

On the evaporation of the solvent from The function ofsuchaplasticizeror signed my name.

the abrasive product, a thin transparent film is left which protects theadhesive from the action of Water, even under very severe conditions.

Another method of carrying out the invention is to apply thenit-ro-cellulose solution to the paper or cloth backing in the samemanner as the glue is commonly applied, and then flow the abrasive grainthereon. The product is then run over or under steam pipes in anenclosure until the volatile vapors evaporate and the film has set.v Theenclosure is arranged with proper facilities for collecting the volatilevapors which are recovered.

The film of abrasive and adhesive on the paper or cloth may then beputinto use or sized with a thin pyroxylin solution to hold the grainsmore firmly in place. I provide an abrasive which is resistant to theaction of water and which may be used'under very severe conditions.

It will be noted that in either case, there is an outer coating ofnitro-cellulose which not only serves to Waterproof the abrasiveproduct, but is also effective for assisting to secure the grains inplace;

The word fabric is used in the claims to designate a flexible backing ofpaper or cloth, such as is employed in the manufacture of sandpaper orsandcloth.

While I have described a preferred 6111" .bodiment of my invention, itwill be understood thatit isnot limited thereto but may be otherwiseembodied within the scope of the following claims.

I claim:

1. An abrasive product comprising a flexible backing having an abrasivematerial at-\ tached "thereto bya glue. and a coating of anitro-cellulose tached thereto by a glue, and a heiat-solidifiedcellulosic composition.

In testimony whereof, I have hereunto I HENRY R. rowan.

compositioncontaining a. modifying agent applied thereto.

